Aqueous dispersions for use as toners

ABSTRACT

A compound that includes an aqueous dispersion, wherein the dispersion includes a thermoplastic resin and at least one stabilizing agent, and at least one selected from the group consisting of a colorant and a magnetic pigment, wherein the dispersion has an average volume diameter particle size from about 0.05 to about 10 microns is described.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.13/192,374, filed Jul. 27, 2011, now U.S. Pat. No. 8,329,812, which wasa division of U.S. application Ser. No. 11/712,206, filed Feb. 28, 2007,now U.S. Pat. No. 8,007,978, which claims priority to U.S. ProvisionalApplication No. 60/779,126, filed Mar. 3, 2006, the disclosure of whichis incorporated herein by reference.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates generally to aqueous dispersions. Morespecifically, the present invention relates to dispersion compounds thatare useful as a print toner.

2. Background Art

In conventional electrophotography processes, a photoreceptive surfaceis charged with a negative electrical charge, which is then exposed toan image. Because the illuminated sections (the image areas) become moreconductive, the charge dissipates in the exposed areas to form a latentimage. Negatively charged toner particles spread over the surface adhereto the latent image area to form a toner image. Alternatively, aphotosensitive surface is uniformly charged with static electricity, anda latent image may be foamed thereon by exposing image area to light.Toner particles are spread over the surface and adhere to thelight-formed latent image, which has less of a negative charge than thesurrounding surface, thereby forming a toner image and making the latentimage visible. If required, the toner image may be transferred onto atransfer material, such as paper. The toner image may then be fixed viafixing means, such as, by heat, pressure, heat and pressure, or solventvapor to obtain a fixed image. Such process is described, for example,in U.S. Pat. No. 2,297,691.

Typically, toners used in the development and subsequent fixing of tonerimages in electrophotography have been produced by melt mixing athermoplastic resin with a coloring agent made of a dye and/or pigmentto produce a resin composition having the coloring agent uniformlydispersed therein. To obtain a toner composition having a particularparticle size, the resin composition may be pulverized and/or classifiedto remove coarse and/or fine particles that may affect the quality ofthe resulting image. Optimizing the particle size distribution of thetoner will allow for a high resolution image. In particular, largerparticles can cause blockage while ultra fine dust particles adhere tothe print head surface and are too small to have enough charge to becontrollable. Thus, as higher resolution images are desired, especiallyhigh resolution color images, smaller particle sizes and narrowerparticle size distributions are needed. Small particles are alsodesirable because they typically result in improved printing speeds andlower costs per page.

The typical pulverization processes for producing these toners, whileable to control the size of the toner particles to produce a highquality toner, often have certain practical limitations. For example,pulverization is a costly and inefficient process for obtaining smallparticle size, and puts constraints on the type of polymer that may beused, so polymers that are excellent in every other respect may beexcluded because they cannot be pulverized. Additionally, a block of aresin composition in which a colorant is dispersed is required to bemicro-pulverized by means of an economically usable production device.However, because the resin composition is fragile, particles having awide range of particle sizes are easily produced when the resincomposition is micro-pulverized at high speed. Additionally, suchfragile material is liable to be further pulverized in a developingapparatus of a copying machine.

Furthermore, in this pulverization process, it is extremely difficult touniformly disperse solid fine particles such as the coloring agent in aresin. Therefore, sufficient attention must be paid to the degree ofdispersion to avoid potential increased fogging, a reduced imagedensity, and decreased color mixing or transparence of the toner,depending on the degree of dispersion. Additionally, the shape andsurface conditions of such toner particles, which may also greatlyaffect the quality of a toner image, are determined by the cleavagefractures of the resultant particles in the pulverization. Specifically,the pulverization process presents difficulties in controlling thesurface conditions of the toner particles, thus when the coloring agentis exposed from the cleavage surface of fine particles of the resincomposition, the quality of the developing image may be reduced.

Therefore, to overcome the problems associated with the pulverizationprocess, it has been previously proposed to produce a chemicallyproduced toner through polymerization, which is described, for example,in U.S. Pat. No. 4,816,366. The polymerization process is a process ofproducing colored polymer particles (i.e., colored resin particles) bymixing a polymerizable monomer with additive components such as acolorant, a charge control agent, and a parting agent to prepare apolymerizable monomer composition and then polymerizing thepolymerizable monomer composition by suspension polymerization, emulsionpolymerization, dispersion polymerization, or the like. Alternatively,chemically produced toners may also be produced by aggregatingpre-formed polymers with the necessary pigment and additives. In thepolymerization processes, the polymer component formed by thepolymerization becomes a binder resin to directly form the coloredpolymer particles.

By eliminating the pulverization step, suspension polymerization oremulsion polymerization can use a softer material for toner particlesthat need not be as fragile. The integrity of the shape of the tonerparticles may be better maintained, which also prevents the coloringagent from being exposed on the surface of the toner particles.Furthermore, the classification step may optionally be omitted; thus,significant cost reduction effects such as energy savings, a reducedproduction time, and an improved step yield may be achieved.

However, toners produced by these polymerization processes are notwithout inherent limitations. For example, these limitations may includehigh capital requirements, that the resulting toners may containresidual monomer or be contaminated with additives, and that limitationson polymer type may exist. Specifically, with respect to the limitationson the types of polymers that may exist, typically, only polymers whichcan be polymerized in the presence of water may be used, thus excludingbroad types of polymers. For example, the polymerization processes ofsome polymers, including some polyolefins, are intolerant of water. Withrespect to residual monomers, it is difficult to completely react thepolymerizable monomer in the polymerization step for forming the binderresin, and thus, an unreacted polymerizable monomer often remains in theresin. As a result, the toner may often contain residual, unreactedmonomer. When the toner containing the residual, polymerizable monomeris used in an image forming apparatus, the polymerizable monomer isvaporized out of the toner by heating in a fixing step to worsen aworking environment or emit offensive odor. When the content of thepolymerizable monomer in the toner is high, the toner also tends toundergo blocking during its storage to aggregate or to cause an offsetphenomenon or toner filming on individual members in the image formingapparatus.

Attempts to remove the polymerizable monomer have varied in theirsuccess due to the various additives that readily absorb any residualpolymerizable monomer in the polymerized toner. The absorbance of theresidual monomer by the additives complicates the removal of theresidual monomer, as compared to removal of monomer from the binderresin alone. Even when the polymerized toner is fully washed after thepolymerization, it is difficult to remove the residual polymerizablemonomer adsorbed within the polymerized toner. Attempts to remove theresidual polymerizable monomer by heat treatment of the polymerizedtoner results in aggregation of the polymerized toner.

U.S. Pat. No. 6,894,090 discloses a toner using certain types of resins,but specifically requires an organic solvent.

Accordingly, there exists a need for compositions and methods of forminghigh performance toner that will produce a high quality image withoutresidual side effects.

SUMMARY OF INVENTION

In one aspect, the present invention relates to a compound that includesan aqueous dispersion, wherein the dispersion includes a thermoplasticresin and at least one stabilizing agent, and at least one selected fromthe group consisting of a colorant and a magnetic pigment, wherein thedispersion has an average volume diameter particle size from about 0.05to about 10 microns.

In another aspect, the present invention relates to a method for forminga toner that includes forming a compound that includes an aqueousdispersion and a colorant, wherein the dispersion includes athermoplastic resin and at least one stabilizing agent, and wherein thedispersion has an average volume diameter particle size from about 0.05to about 10 microns and removing at least a portion of the water in thedispersion to form toner particles.

Other aspects and advantages of the invention will be apparent from thefollowing description and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows an extruder that may be used in formulating dispersions inaccordance with embodiments of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention relate to aqueous dispersions andcompounds made from aqueous dispersions that are useful as tonercompositions. Dispersions used in embodiments of the present inventioncomprise water, (A) at least one thermoplastic resin, and (B) astabilizing agent. These are discussed in more detail below. Thecompounds involve an aqueous dispersion and the addition of at least oneof a colorant and a magnetic pigment, and may further include a numberof additives. These components in the compound are discussed in moredetail below.

Thermoplastic Resin

The thermoplastic resin (A) included in embodiments of the aqueousdispersion of the present invention is a resin that is not readilydispersible in water by itself. The term “resin,” as used herein, shouldbe construed to include synthetic polymers or chemically modifiednatural resins such as, but not limited to, thermoplastic materials suchas polyvinyl chloride, polystyrene, polyesters, styrene acrylates, andpolyethylene and thermosetting materials such as polyesters, epoxies,and silicones that are used with fillers, stabilizers, pigments, andother components to form plastics.

The term resin as used herein also includes elastomers and is understoodto include blends of olefin polymers. In some embodiments, thethermoplastic resin is a semicrystalline resin. The term“semi-crystalline” is intended to identify those resins that possess atleast one endotherm when subjected to standard differential scanningcalorimetry (DSC) evaluation. Some semi-crystalline polymers exhibit aDSC endotherm that exhibits a relatively gentle slope as the scanningtemperature is increased past the final endotherm maximum. This reflectsa polymer of broad melting range rather than a polymer having what isgenerally considered to be a sharp melting point. Some thermoplasticresins useful in the dispersions of the invention have a single meltingpoint while other polymers have more than one melting point.

In some thermoplastic resins, one or more of the melting points may besharp such that all or a portion of the polymer melts over a fairlynarrow temperature range, such as a few degrees centigrade. In otherembodiments, the thermoplastic resins may exhibit broad meltingcharacteristics over a range of about 20° C. In yet other embodiments,the thermoplastic resins may exhibit broad melting characteristics overa range of greater than 50° C.

In certain other embodiments, the thermoplastic resin may have a densitybetween 0.8 and 1.5 g/cc. In other embodiments, the thermoplastic resinmay have a density between 0.85 and 1.4 g/cc; between 0.86 and 1.3 g/ccin other embodiments, and between 0.87 and 1.2 g/cc in yet otherembodiments.

Examples of the thermoplastic resin (A) that may be used in the presentinvention include homopolymers and copolymers (including elastomers) ofan alpha-olefin such as ethylene, propylene, 1-butene,3-methyl-1-butene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-heptene,1-hexene, 1-octene, 1-decene, and 1-dodecene, as typically representedby polyethylene, polypropylene, poly-1-butene, poly-3-methyl-1-butene,poly-3-methyl-1-pentene, poly-4-methyl-1-pentene, ethylene-propylenecopolymer, ethylene-1-butene copolymer, and propylene-1-butenecopolymer; copolymers (including elastomers) of an alpha-olefin with aconjugated or non-conjugated diene, as typically represented byethylene-butadiene copolymer and ethylene-ethylidene norbornenecopolymer; and polyolefins (including elastomers) such as copolymers oftwo or more alpha-olefins with a conjugated or non-conjugated diene, astypically represented by ethylene-propylene-butadiene copolymer,ethylene-propylene-dicyclopentadiene copolymer,ethylene-propylene-1,5-hexadiene copolymer, andethylene-propylene-ethylidene norbornene copolymer; ethylene-vinylcompound copolymers such as ethylene-vinyl acetate copolymer,ethylene-vinyl alcohol copolymer, ethylene-vinyl chloride copolymer,ethylene acrylic acid or ethylene-(meth)acrylic acid copolymers, andethylene-(meth)acrylate copolymer; styrenic copolymers (includingelastomers) such as polystyrene, ABS, acrylonitrile-styrene copolymer,α-methylstyrene-styrene copolymer, styrene vinyl alcohol, styreneacrylates such as styrene methylacrylate, styrene butyl acrylate,styrene butyl methacrylate, and styrene butadienes and crosslinkedstyrene polymers; and styrene block copolymers (including elastomers)such as styrene-butadiene copolymer and hydrate thereof, andstyrene-isoprene-styrene triblock copolymer; polyvinyl compounds such aspolyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinylidenechloride copolymer, polymethyl acrylate, and polymethyl methacrylate;polyamides such as nylon 6, nylon 6,6, and nylon 12; thermoplasticpolyesters such as polyethylene terephthalate and polybutyleneterephthalate; polycarbonate, polyphenylene oxide, and the like; andglassy hydrocarbon-based resins, including poly-dicyclopentadienepolymers and related polymers (copolymers, terpolymers); saturatedmono-olefins such as vinyl acetate, vinyl propionate and vinyl butyrateand the like; vinyl esters such as esters of monocarboxylic acids,including methyl acrylate, ethyl acrylate, n-butylacrylate, isobutylacrylate, dodecyl acrylate, n-octyl acrylate, phenyl acrylate, methylmethacrylate, ethyl methacrylate, and butyl methacrylate and the like;acrylonitrile, methacrylonitrile, acrylamide, mixtures thereof; resinsproduced by ring opening metathesis and cross metathesis polymerizationand the like. These resins may be used either alone or in combinationsof two or more. Examples of specific thermoplastic toner resins includestyrene butadiene copolymers with a styrene content of from about 70 toabout 95 weight percent.

Thermoplastic resins may include polymers containing at least one esterbond. For example, polyester polyols may be prepared via a conventionalesterification process using a molar excess of an aliphatic diol orglycol with relation to an alkanedioic acid. Illustrative of the glycolsthat can be employed to prepare the polyesters are ethylene glycol,diethylene glycol; propylene glycol, dipropylene glycol,1,3-propanediol, 1,4-butanediol and other butanediols, 1,5-pentanedioland other pentane diols, hexanediols, decanediols, and dodecanediols. Insome embodiments, the aliphatic glycol may contain from 2 to about 8carbon atoms. Illustrative of the dioic acids that may be used toprepare the polyesters are maleic acid, malonic acid, succinic acid,glutaric acid, adipic acid, 2-methyl-1,6-hexanoic acid, pimelic acid,suberic acid, and dodecanedioic acids. In some embodiments, thealkanedioic acids may contain from 4 to 12 carbon atoms. Illustrative ofthe polyester polyols are poly(hexanediol adipate), polybutylene glycoladipate), poly(ethylene glycol adipate), poly(diethylene glycoladipate), poly(hexanediol oxalate), and poly(ethylene glycol sebecate.

As another example, polyester resins obtained by condensation of adicarboxylic acid components (these dicarboxylic acid components may besubstituted by a sulfonic acid group, a carboxyl group, and the like)and alcoholic components (these alcoholic components may be substitutedby the hydroxyl group, and the like), polyacrylic acid ester resins orpolymethacrylic acid ester resins such as polymethylmethacrylate,polybutylmethacrylate, polymethylacrylate, polybutylacrylate, and thelike; polycarbonate resin, polyvinyl acetate resin, styrene acrylateresin, styrene-methacrylic acid ester copolymer resin, vinyltolueneacrylate resin, and the like.

Thermoplastic resins may include homopolymers and copolymers of styreneand derivatives thereof such as polystyrene, poly-p-chlorostyrene,polyvinyltoluene, styrene-p-chlorostyrene copolymer and styrenevinyltoluene copolymer, copolymers of styrene and acrylates such asstyrene methylacrylate copolymer, styrene ethylacrylate copolymer, andstyrene-n-butyl acrylate copolymer; copolymers of styrene andmethacrylate such as styrene-methylmethacrylate copolymer,styrene-ethylmethacrylate copolymer, and styrene-n-butylmethacrylatecopolymer; polynary copolymers of styrene, acrylate and methacrylate; aswell as styrenic copolymers such as copolymers of styrene and othervinylic monomer, such as styrene-acrylonitrile copolymer,styrene-vinylmethyl ether copolymer, styrene-butadiene copolymer,styrene-vinyl methyl ketone copolymer, styrene-acrylonitrile-indenecopolymer and styrene-maleate copolymer; polymethyl methacrylate,polybutyl methacrylate, polyvinyl acetate, polyester, polyamide, epoxyresin, polyvinyl butyral, polyacrylic acid, phenolic resin, aliphatic orcycloaliphatic hydrocarbon resin, petroleum resin and chlorinatedparaffin, which may be used alone or may be used in an appropriatecombination thereof.

Thermoplastic resins may include suitable non-conjugated diene monomerssuch as straight chain, branched chain or cyclic hydrocarbon dienehaving from 6 to 15 carbon atoms. Examples of suitable non-conjugateddienes include, but are not limited to, straight chain acyclic dienes,such as 1,4-hexadiene, 1,6-octadiene, 1,7-octadiene, 1,9-decadiene,branched chain acyclic dienes, such as 5-methyl-1,4-hexadiene;3,7-dimethyl-1,6-octadiene; 3,7-dimethyl-1,7-octadiene and mixed isomersof dihydromyricene and dihydroocinene, single ring alicyclic dienes,such as 1,3-cyclopentadiene; 1,4-cyclohexadiene; 1,5-cyclooctadiene and1,5-cyclododecadiene, and multi-ring alicyclic fused and bridged ringdienes, such as tetrahydroindene, methyl tetrahydroindene,dicyclopentadiene, bicyclo-(2,2,1)-hepta-2,5-diene; alkenyl, alkylidene,cycloalkenyl and cycloalkylidene norbornenes, such as5-methylene-2-norbornene (MNB); 5-propenyl-2-norbornene,5-isopropylidene-2-norbornene, 5-(4-cyclopentenyl)-2-norbornene,5-cyclohexylidene-2-norbornene, 5-vinyl-2-norbornene, and norbornadiene.Of the dienes typically used to prepare EPDMs, the particularlypreferred dienes are 1,4-hexadiene (HD), 5-ethylidene-2-norbornene(ENB), 5-vinylidene-2-norbornene (VNB), 5-methylene-2-norbornene (MNB),and dicyclopentadiene (DCPD).

One class of desirable thermoplastic resins that may be used inaccordance with embodiments disclosed herein includes elastomericinterpolymers of ethylene, a C₃-C₂₀ α-olefin, especially propylene, andoptionally one or more diene monomers. Preferred α-olefins for use inthis embodiment are designated by the formula CH₂═CHR*, where R* is alinear or branched alkyl group of from 1 to 12 carbon atoms. Examples ofsuitable α-olefins include, but are not limited to, propylene,isobutylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, and1-octene. The propylene-based polymers are generally referred to in theart as EP or EPDM polymers. Suitable dienes for use in preparing suchpolymers, especially multi block EPDM type polymers, include conjugatedor non-conjugated, straight or branched chain-, cyclic- orpolycyclic-dienes comprising from 4 to 20 carbon atoms. Dienes mayinclude 1,4-pentadiene, 1,4-hexadiene, 5-ethylidene-2-norbornene,dicyclopentadiene, cyclohexadiene, and 5-butylidene-2-norbornene.

As one suitable type of thermoplastic resin, the esterification productsof a di- or poly-carboxylic acid and a diol comprising a diphenol may beused. These resins are illustrated in U.S. Pat. No. 3,590,000, which isincorporated herein by reference. Other specific examples of tonerresins include styrene/methacrylate copolymers, and styrene/butadienecopolymers; suspension polymerized styrene butadienes; polyester resinsobtained from the reaction of bisphenol A and propylene oxide followedby the reaction of the resulting product with fumaric acid; and branchedpolyester resins resulting from the reaction of dimethylterphthalate,1,3-butanediol, 1,2-propanediol, and pentaerythritol, styrene acrylates,and mixtures thereof.

Further, specific embodiments of the present invention employethylene-based polymers, propylene-based polymers, propylene-ethylenecopolymers, and styrenic copolymers as one component of a composition.Other embodiments of the present invention use polyester resins,including those containing aliphatic diols such as UNOXOL 3,4 diolavailable from The Dow Chemical Company (Midland, Mich.).

In selected embodiments, one component is formed from ethylene-alphaolefin copolymers or propylene-alpha olefin copolymers. In particular,in select embodiments, the thermoplastic resin comprises one or morenon-polar polyolefins.

In specific embodiments, polyolefins such as polypropylene,polyethylene, copolymers thereof, and blends thereof, as well asethylene-propylene-diene terpolymers, may be used. In some embodiments,preferred olefinic polymers include homogeneous polymers, as describedin U.S. Pat. No. 3,645,992 issued to Elston; high density polyethylene(HDPE), as described in U.S. Pat. No. 4,076,698 issued to Anderson;heterogeneously branched linear low density polyethylene (LLDPE);heterogeneously branched ultra low linear density polyethylene (ULDPE);homogeneously branched, linear ethylene/alpha-olefin copolymers;homogeneously branched, substantially linear ethylene/alpha-olefinpolymers, which can be prepared, for example, by processes disclosed inU.S. Pat. Nos. 5,272,236 and 5,278,272, the disclosures of which areincorporated herein by reference; and high pressure, free radicalpolymerized ethylene polymers and copolymers such as low densitypolyethylene (LDPE) or ethylene vinyl acetate polymers (EVA).

Polymer compositions, and blends thereof, described in U.S. Pat. Nos.6,566,446, 6,538,070, 6,448,341, 6,316,549, 6,111,023, 5,869,575,5,844,045, or 5,677,383, each of which is incorporated herein byreference in its entirety, may also be suitable in some embodiments. Insome embodiments, the blends may include two different Ziegler-Nattapolymers. In other embodiments, the blends may include blends of aZiegler-Natta polymer and a metallocene polymer. In still otherembodiments, the thermoplastic resin used herein may be a blend of twodifferent metallocene polymers. In other embodiments, single sitecatalyst polymers may be used.

In some embodiments, the thermoplastic resin is a propylene-basedcopolymer or interpolymer. In some particular embodiments, thepropylene/ethylene copolymer or interpolymer is characterized as havingsubstantially isotactic propylene sequences. The term “substantiallyisotactic propylene sequences” and similar terms mean that the sequenceshave an isotactic triad (mm) measured by 13C NMR of greater than about0.85, preferably greater than about 0.90, more preferably greater thanabout 0.92 and most preferably greater than about 0.93. Isotactic triadsare well-known in the art and are described in, for example, U.S. Pat.No. 5,504,172 and WO 00/01745, which refer to the isotactic sequence interms of a triad unit in the copolymer molecular chain determined by 13CNMR spectra.

In other particular embodiments, the thermoplastic resin may be ethylenevinyl acetate (EVA) based polymers. In other embodiments, the basepolymer may be ethylene-methyl acrylate (EMA) based polymers. In otherparticular embodiments, the ethylene-alpha olefin copolymer may beethylene-butene, ethylene-hexene, or ethylene-octene copolymers orinterpolymers. In other particular embodiments, the propylene-alphaolefin copolymer may be a propylene-ethylene or apropylene-ethylene-butene copolymer or interpolymer.

Embodiments disclosed herein may also include a polymeric component thatmay include at least one multi-block olefin interpolymer. Suitablemulti-block olefin interpolymers may include those described in, forexample, U.S. Provisional Patent Application No. 60/818,911,incorporated herein by reference. The term “multi-block copolymer” or“multi-block interpolymer” refers to a polymer comprising two or morechemically distinct regions or segments (referred to as “blocks”)preferably joined in a linear manner, that is, a polymer comprisingchemically differentiated units which are joined end-to-end with respectto polymerized ethylenic functionality, rather than in pendent orgrafted fashion. In certain embodiments, the blocks differ in the amountor type of comonomer incorporated therein, the density, the amount ofcrystallinity, the crystallite size attributable to a polymer of suchcomposition, the type or degree of tacticity (isotactic orsyndiotactic), regio-regularity or regio-irregularity, the amount ofbranching, including long chain branching or hyper-branching, thehomogeneity, or any other chemical or physical property.

Other olefin interpolymers include polymers comprising monovinylidenearomatic monomers including styrene, o-methyl styrene, p-methyl styrene,t-butylstyrene, and the like. In particular, interpolymers comprisingethylene and styrene may be used. In other embodiments, copolymerscomprising ethylene, styrene and a C₃-C₂₀ α-olefin, optionallycomprising a C₄-C₂₀ diene, may be used.

In certain embodiments, the thermoplastic resin may be anethylene-octene copolymer or interpolymer having a density between 0.863and 0.911 g/cc and melt index (ASTM D1238, 190° C. with 2.16 kg weight)from 0.1 to 100 g/10 min. In other embodiments, the ethylene-octenecopolymers may have a density between 0.863 and 0.902 g/cc and meltindex (ASTM D1238, 190° C. with 2.16 kg weight) from 0.8 to 35 g/10 min.

In certain embodiments, the thermoplastic resin may be apropylene-ethylene copolymer or interpolymer having an ethylene contentbetween 5 and 20% by weight and a melt flow rate (ASTM D1238, 230° C.with 2.16 kg weight) from 0.5 to 300 g/10 min. In other embodiments, thepropylene-ethylene copolymer or interpolymer may have an ethylenecontent between 9 and 12% by weight and a melt flow rate (ASTM D1238,230° C. with 2.16 kg weight) from 1 to 100 g/10 min.

In certain other embodiments, the thermoplastic resin may be a highlybranched low density polyethylene having a density between 0.911 and0.925 g/cc and melt index (ASTM D1238, 190° C. with 2.16 kg weight) from0.1 to 100 g/10 min.

In other embodiments, the thermoplastic resin may have a crystallinityof less than 50 percent. In preferred embodiments, the crystallinity ofthe thermoplastic resin may be from 5 to 35 percent. In more preferredembodiments, the crystallinity may range from 7 to 20 percent.

In certain other embodiments, the thermoplastic resin is asemi-crystalline polymer and may have a melting point of less than 110°C. In preferred embodiments, the melting point may be from 25 to 100° C.In more preferred embodiments, the melting point may be between 40 and85° C.

In other embodiments, the thermoplastic resin is a glassy polymer andmay have a glass transition temperature of less than 130° C.; less than110° C. in other embodiments. In preferred embodiments, the glasstransition temperature may be from 20 to 100° C. In more preferredembodiments, the glass transition temperature may be from 50 to 75° C.

In certain embodiments, the thermoplastic resin may have a weightaverage molecular weight greater than 10,000 g/mole. In otherembodiments, the weight average molecular weight may be from 20,000 to150,000 g/mole; in yet other embodiments, from 50,000 to 100,000 g/mole.

The one or more thermoplastic resins may be contained within the aqueousdispersion in an amount from about 1% by weight to about 96% by weight.For instance, during particle formation, the thermoplastic resin may bepresent in the aqueous dispersion in an amount from about 40% by weightto about 95% by weight, such as from about 45% to 90% by weight in someembodiments, and from about 60% to about 80% by weight in yet otherembodiments. After particle formation, the dispersion can be furtherdiluted to aid in handling.

In one or more embodiments of the present invention, one or more resinsselected from the following may be used in the dispersion disclosedherein to form a toner composition. Suitable resins include SAA100,SAA101, and SAA104, which are commercially available from LyondellChemical and comprise styrenic/allyl alcohol copolymers having 60-80%styrene, weight average molecular weight from 3,000 to 8,000, numberaverage molecular weight from 1,500 to 3,200, and glass transitiontemperature from 57 to 78° C.; the DIANAL® FB series (styrenic-acryliccopolymers) and DIACRON® series (polyester resins), and acrylic resinsincluding SE-5437, SE-5102, SE-5377, SE-5649, SE-5466, SE-5482, HR-169,124, HR-1127, HR-116, HR-113, HR-148, HR-131, HR-470, HR-634, HR-606,HR-607, LR-1065, 574, 143, 396, 637, 162, 469, 216, BR-50, BR-52, BR-60,BR-64, BR-73, BR-75, BR-77, BR-79, BR-80, BR-83, BR-85, BR-87, BR-88,BR-90, BR-93, BR-95, BR-100, BR-101, BR-102, BR-105, BR-106, BR-107,BR-108, BR-112, BR-113, BR-115, BR-116, BR-117, which are commerciallyavailable from Misubishi Rayon Co Ltd. and its subsidiary DianalAmerica, Inc.; Himer ST95 and ST120, which are acrylic copolymerscommercially available from Sanyo Chemical Industries, Ltd.; FM601,which is an acrylic resin commercially available from Mitsui Chemicals;HRJ11441, which is a branched partially crosslinked polyester resincommercially available from Schenectady Intl; TUFTONE® NE-382, TUFTONE®U-5, ATR-2009, and ATR-2010, which are polyester resins commerciallyavailable from Kao Specialties Americas, LLC; S103C and S111, which arestyrene acrylonitrile terpolymers commercially available from ZeonChemicals, LP; LUPRETON® resins, which polyester resins with colorconcentrates commercially available from BASF Corp.; FINE-TONE®T382ESHHMW, T382ES, T6694, TCX 100, TCX700, TPL400TRM70, which arepolyester resins commercially available from Reichhold Chemicals, Inc.;TOPAS® TM, TOPAS® TB, and TOPAS® 8007, which are cyclic olefincopolymers commercially available from Ticona GMBH Corp.; S-LEC resins,including SE-0020, SE-0030, SE-0040, SE-0070, SE-0080, SE-0090, SE-0100,SE-1010, and SE-1035, which are styrene-acrylic copolymers commerciallyavailable from Sekisui Chemical Co., Ltd.; BAILON 290, BAILON 200,BAILON 300, BAILON 103, BAILON GK-140, and BAILON GK-130 which arecommercially available from Toyobo Co., Ltd; Eritel UE3500, UE3210, andXA-8153, which are commercially available from Unitika Ltd.; andPolyester TP-220 and R-188, which are commercially available from TheNippon Synthetic Chemical Industry Co., Ltd.

Those having ordinary skill in the art will recognize that the abovelist is a non-comprehensive listing of suitable polymers. It will beappreciated that the scope of the present invention is restricted by theclaims only.

Stabilizing Agent

Embodiments of the present invention use a stabilizing agent to promotethe formation of a stable dispersion or emulsion. In selectedembodiments, the stabilizing agent may be a surfactant, a polymer(different from the thermoplastic resin detailed above), or mixturesthereof. In other embodiments, the thermoplastic resin is aself-stabilizer, so that an additional exogenous stabilizing agent maynot be necessary. For example, a self-stabilizing system may include apartially hydrolyzed polyester, where by combining polyester with anaqueous base, a polyester resin and surfactant-like stabilizer moleculemay be produced. In addition, stabilizing agents may be used alone or ina combination of two or more.

In certain embodiments, the stabilizing agent may be a polar polymer,having a polar group as either a comonomer or grafted monomer. Inpreferred embodiments, the stabilizing agent may include one or morepolar polyolefins, having a polar group as either a comonomer or graftedmonomer. Typical polymers include ethylene-acrylic acid (EAA) andethylene-methacrylic acid copolymers, such as those available under thetrademarks PRIMACOR™ (trademark of The Dow Chemical Company), NUCREL™(trademark of E.I. DuPont de Nemours), and ESCOR™ (trademark ofExxonMobil) and described in U.S. Pat. Nos. 4,599,392, 4,988,781, and5,938,437, each of which is incorporated herein by reference in itsentirety. Other suitable polymers include ethylene-ethyl acrylate (EEA)copolymer, ethylene-methyl methacrylate (EMMA), and ethylene-butylacrylate (EBA). Other ethylene-carboxylic acid copolymers may also beused. Those having ordinary skill in the art will recognize that anumber of other useful polymers may also be used.

If the polar group of the polymer is acidic or basic in nature, thestabilizing polymer may be partially or fully neutralized with aneutralizing agent to form the corresponding salt. The salts may bealkali metal or ammonium salts of the fatty acid, prepared byneutralization of the acid with the corresponding base, e.g., NaOH, KOH,and NH₄OH. These salts may be formed in situ in the dispersion step, asdescribed more fully below. In certain embodiments, neutralization ofthe stabilizing agent, such as a long chain fatty acid or EAA, may befrom 10 to 200% on a molar basis; from 25 to 200% on a molar basis inother embodiments; from 20 to 110% on a molar basis in otherembodiments, and from 50 to 110% on a molar basis in yet otherembodiments. For example, for EAA, the neutralizing agent is a base,such as ammonium hydroxide or potassium hydroxide. Other neutralizingagents can include lithium hydroxide or sodium hydroxide, for example.Those having ordinary skill in the art will appreciate that theselection of an appropriate neutralizing agent depends on the specificcomposition formulated, and that such a choice is within the knowledgeof those of ordinary skill in the art.

Other surfactants that may be used include long chain fatty acids orfatty acid salts having from 12 to 60 carbon atoms. In otherembodiments, the long chain fatty acid or fatty acid salt may have from12 to 40 carbon atoms.

Additional surfactants that may be useful in the practice of the presentinvention include cationic surfactants, anionic surfactants, non-ionicsurfactants, or combinations thereof. Examples of anionic surfactantsinclude sulfonates, carboxylates, and phosphates. Examples of cationicsurfactants include quaternary amines. Examples of non-ionic surfactantsinclude block copolymers containing ethylene oxide and siliconesurfactants. Surfactants useful as a stabilizing agent may be eitherexternal surfactants or internal surfactants. External surfactants aresurfactants that do not become chemically reacted into the polymerduring dispersion preparation. Examples of external surfactants usefulherein include salts of dodecyl benzene sulfonic acid and laurylsulfonic acid. Internal surfactants are surfactants that do becomechemically reacted into the polymer during dispersion preparation. Anexample of an internal surfactant useful herein includes 2,2-dimethylolpropionic acid and its salts or sulfonated polyols neutralized withammonium chloride.

In particular embodiments, the dispersing agent or stabilizing agent maybe used in an amount ranging from greater than zero to about 60% byweight based on the amount of thermoplastic resin (or thermoplasticresin mixture) used. With respect to the thermoplastic resin and thedispersion stabilizing agent, in some embodiments, the thermoplasticresin may comprise between about 30% to 99% (by weight) of the totalamount of thermoplastic resin and dispersion stabilizing agent in thecomposition. In other embodiments, the thermoplastic resin may comprisebetween about 50% and about 80% (by weight) of the total amount ofthermoplastic resin and dispersion stabilizing agent in the composition.In yet other embodiments, the thermoplastic resins may comprise about70% (by weight) of the total amount of thermoplastic resin anddispersion stabilizing agent in the composition. For example, long chainfatty acids or salts thereof may be used from 0.5 to 10% by weight basedon the amount of thermoplastic resin. In other embodiments,ethylene-acrylic acid or ethylene-methacrylic acid copolymers may beused in an amount from 0.5 to 60% by weight based on the amount of thethermoplastic resin. In yet other embodiments, sulfonic acid salts maybe used in an amount from 0.5 to 10% by weight based on the amount ofthermoplastic resin.

Colorant

Embodiments of the present invention may employ a colorant as part ofthe composition. A variety of colors may be used. Typically, colors suchas yellow, magenta, and cyan may be used. As a black coloring agent,carbon black, a magnetic material, and a coloring agent toned to blackusing the yellow/magenta/cyan coloring agents shown below may be used.

As a yellow coloring agent, compounds typified by a condensed azocompound, an isoindolynone compound, an anthraquinone compound, anazometal complex methine compound, and an allylamide compound aspigments may be used. Specifically, C.I. pigment yellows 3, 7, 10, 12 to15, 17, 23, 24, 60, 62, 74, 75, 83, 93 to 95, 99, 100, 101, 104, 108 to111, 117, 123, 128, 129, 138, 139, 147, 148, 150, 166, 168 to 177, 179,180, 181, 183, 185, 191:1, 191, 192, 193, and 199 may be suitable foruse as a yellow coloring agent. Examples of dyes include C.I. solventyellows 33, 56, 79, 82, 93, 112, 162, and 163, and C.I. disperse yellows42, 64, 201, and 211.

As a magenta coloring agent, a condensed azo compound, adiketopyrrolopyrrole compound, anthraquinone, a quinacridone compound, abase dye lake compound, a naphthol compound, a benzimidazolone compound,a thioindigo compound, and a perylene compound may be used.Specifically, C.I. pigment reds 2, 3, 5 to 7, 23, 48:2, 48:3, 48:4,57:1, 81:1, 122, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, and254, and C.I. pigment violet 19 may be suitable for use as a magentacoloring agent.

As a cyan coloring agent, a copper phthalocyanine compound and itsderivative, an anthraquinone compound, a base dye lake compound, and thelike may be used. Specifically, C.I. pigment blues 1, 7, 15, 15:1, 15:2,15:3, 15:4, 60, 62, and 66 may be suitable for use as a cyan coloringagent.

These coloring agents may be used singly, in mixture, or as a solidsolution. The coloring agent of the present invention is selected interms of the hue angle, saturation, brightness, weather resistance, OHPtransparency, and dispersibility into the toner. The coloring agent maybe added in an amount of 0.5 to 20 parts by weight based on 100 parts byweight of the thermoplastic resin.

Magnetic Pigment

Further, the toner of the present invention may contain a magneticmaterial and be used as a magnetic toner. In this case, the magneticmaterial may also function as a coloring agent. Examples of the magneticmaterial contained in a magnetic toner in the present invention includeiron oxides such as magnetite, hematite, and ferrite; metals such asiron, cobalt, and nickel, or alloys of these metals with metals such asaluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony,beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium,tungsten, and vanadium; and mixtures thereof.

The magnetic material used in the present invention may preferably be asurface modified magnetic material. Examples of surface modifiers thatmay be used to hydrophobically treat magnetic material include a silanecoupling agent and a titanium coupling agent.

The magnetic material used in the compounds disclosed here may have amean particle size of 2 μm or smaller, preferably from 0.1 to 0.5 μm.The magnetic material may be included in the compound in an amountranging from 20 to 200 parts by weight, preferably from 40 to 150 partsby weight, based on 100 parts by weight of the thermoplastic resin.

The magnetic material preferably has magnetic properties when 796 kA/m(10 k oersted) is applied such as a coercive force (He) of 1.59 to 23.9kA/m (20 to 300 oersted), a saturation magnetization (as) of 50 to 200emu/g, and a remnant magnetization (or) of 2 to 20 emu/g.

Charge Control Agent

In certain embodiments of the present invention, a charge control agentmay be included in the compounds disclosed herein. Examples of a chargecontrol agent used to control the charge to be negative include anorganometallic compound, a chelate compound, a monoazometallic compound,an acetylacetone metallic compound, a urea derivative, ametal-containing salicylic acid compound, a metal-containing naphthoicacid compound, a tertiary ammonium salt, calixarene, a silicon compound,and a non-metal carboxylic acid compound and its derivative.

Examples of a charge control agent used to control the charge to bepositive include nigrosine and its modified product by a fatty acidmetal salt; quaternary ammonium salts such astributylbenzylammonium-1-hydroxy-4-naph-thosulfonate andtetrabutylammonium tetrafluoroborate, and onium salts and theiranalogues such as a phosphonium salt, and their lake pigments, andtriphenylmethane dyes and their lake pigments, of which laking agentsinclude phosphotungstic acid, phosphomolybdic acid,phosphotungsticmolybdic acid, tannic acid, lauric acid, gallic acid, aferricyanide, and a ferrocyanide; metal salts of higher fatty acids;diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, anddicyclohexyltin oxide; and diorganotin borates such as dibutyltinborate, dioctyltin borate, and dicyclohexyltin borate. These may be usedsingly or in a combination of two or more. Of these, charge controlagents such as nigrosins and quaternary ammonium salts may bepreferable.

The toner compound may include a charge control agent in an amountranging from 0.01 to 20 parts by weight, preferably from 0.5 to 10 partsby weight, based on 100 parts by weight of the thermoplastic resin inthe toner.

Other Additives

A number of other additives, known to those of ordinary skill in theart, may be used in embodiments of the present invention. For example,an additive may be used in order to improve various properties of thetoner. Examples of such additives include metal oxides such as siliconoxide, aluminum oxide, titanium oxide, and hydrotalcite; carbon black,and fluorocarbon. Preferably, these additives may be hydrophobicallytreated.

Other additives that may be used to improve various properties of thetoner include waxes such as metallocene waxes and polypropylene waxes.

A polishing agent may be used in accordance with embodiments of thepresent invention. Typical polishing agents include strontium titanate;metal oxides such as cerium oxide, aluminum oxide, magnesium oxide, andchromium oxide; nitrides such as silicon nitride; carbides such assilicon carbide; and metal salts such as calcium sulfate, bariumsulfate, and calcium carbonate.

A lubricant may be used in accordance with embodiments of the presentinvention. Typically lubricants include fluororesin powders such asvinylidene fluoride and polytetrafluoroethylene; and fatty acid metalsalts such as zinc stearate and calcium stearate.

Additionally, charge controlling particles include metal oxides such astin oxide, titanium oxide, zinc oxide, silicon oxide, and aluminumoxide; and carbon black.

These additives may be used in an amount ranging from 0.1 to 10 parts byweight, preferably from 0.1 to 5 parts by weight, based on 100 parts byweight of the toner particles. These external additives may be usedsingly or in a combination.

Formulations

In preferred formulations, dispersions in accordance with the presentinvention. may include a thermoplastic resin, a stabilizing agent (whichmay be polymeric or a surfactant), and at least one of a colorant and amagnetic pigment. A number of other additives, depending on theparticular formulation, and the nature of the toner to be produced mayalso be used.

In one embodiment, a thermoplastic resin, a stabilizing agent, and atleast one of a colorant and a magnetic pigment are melt-kneaded in anextruder along with water and a neutralizing agent, such as ammonia,potassium hydroxide, or a combination of the two to form a dispersioncompound. The additives may be mixed with the thermoplastic resin eitherduring or prior to the formation of the dispersion and/or extrusion.Those having ordinary skill in the art will recognize that a number ofother neutralizing agents may be used. In some embodiments, the at leastone of a colorant and a magnetic pigment may be added after blending thethermoplastic resin and stabilizing agent. in other preferredembodiments, the at least one of a colorant and a magnetic pigment maybe added after the dispersion is formed. In addition, any other suitableadditive (such as any of those discussed above) may be added to thecomposition prior to the formation of the dispersion.

In another embodiment, a thermoplastic resin, such as a self-stabilizingresin, and at least one of a colorant and a magnetic pigment aremelt-kneaded in an extruder along with water and a neutralizing agent,such as ammonia, potassium hydroxide, or a combination of the two toform a dispersion compound. In yet another embodiment, a thermoplasticresin, a stabilizing agent, and at least one of a colorant and amagnetic pigment are melt-kneaded in an extruder along with waterwithout use of a neutralizing agent to form a dispersion compound.

Any melt-kneading means known in the art may be used. In someembodiments, a kneader, a BANBURY® mixer, a single-screw extruder, or amulti-screw extruder is used. A process for producing the dispersions inaccordance with the present invention is not particularly limited. Anyreference to use of an extruder herein is not intended to be alimitation on the present invention. One preferred process, for example,is a process comprising melt-kneading the above-mentioned componentsaccording to U.S. Pat. No. 5,756,659 and U.S. Pat. No. 6,455,636, whichare herein incorporated by reference in their entirety. An alternativeexample in which an extruder is not required allows for the mechanicaldispersion to be formed in a high shear mixer. The high shear mixer maybe specifically applicable to dispersions using polyesters and somestyrenic copolymers, for example.

FIG. 1 schematically illustrates an extrusion apparatus that may be usedin embodiments of the invention. An extruder 20, in certain embodimentsa twin screw extruder, is coupled to a back pressure regulator, meltpump, or gear pump 30. Embodiments also provide a base reservoir 40 andan initial water reservoir 50, each of which includes a pump (notshown). Desired amounts of base and initial water are provided from thebase reservoir 40 and the initial water reservoir 50, respectively. Anysuitable pump may be used, but in some embodiments a pump that providesa flow of about 150 cc/min at a pressure of 240 bar is used to providethe base and the initial water to the extruder 20. In other embodiments,a liquid injection pump provides a flow of 300 cc/min at 200 bar or 600cc/min at 133 bar. In some embodiments, the base and initial water arepreheated in a preheater.

Thermoplastic resin in the form of pellets, powder or flakes is fed fromthe feeder 80 to an inlet 90 of the extruder 20 where the thermoplasticresin is melted or compounded. In some embodiments, the dispersing agentis added to the thermoplastic resin through and along with thethermoplastic resin and in other embodiments, the dispersing agent isprovided separately to the twin screw extruder 20. The thermoplasticresin melt is then delivered from the mix and convey zone to anemulsification zone of the extruder where the initial amount of waterand base from the reservoirs 40 and 50 is added through inlet 55. Insome embodiments, dispersing agent may be added additionally orexclusively to the water stream. In some embodiments, the emulsifiedmixture is further diluted with additional water through inlet 95 fromreservoir 60 in a dilution and cooling zone of the extruder 20.Typically, the dispersion is diluted to at least 30 weight percent waterin the cooling zone. In addition, the diluted mixture may be diluted anynumber of times until the desired dilution level is achieved. In someembodiments, water is not added into the twin screw extruder 20 butrather to a stream containing the resin melt after the melt has exitedfrom the extruder. In this manner, steam pressure build-up in theextruder 20 is eliminated.

Advantageously, by using an extruder in certain embodiments, thethermoplastic resin and the stabilizing agent may be blended in a singleprocess to form a dispersion. Also, advantageously, by using one or moreof the stabilizing agents listed above, the dispersion is stable withrespect to the additives.

Dispersions formed in accordance with embodiments of the presentinvention are characterized as having an average particle size ofbetween about 0.05 to about 10 microns. In other embodiments, thedispersion may have an average particle size between about 0.05 to about8.0 microns. In other embodiments, dispersions have an average particlesize of from about 0.1 to about 6.0 microns. As used herein, “averageparticle size” refers to the volume-mean particle size. In order tomeasure the particle size, laser-diffraction techniques may be employed,for example. A particle size in this description refers to the diameterof the polymer in the dispersion. For polymer particles that are notspherical, the diameter of the particle is the average of the long andshort axes of the particle. Particle sizes can be measured, for example,on a Beckman-Coulter LS230 laser-diffraction particle size analyzer orother suitable device. In one embodiment, the desired particle sizes maybe obtained by forming very small particles and aggregating these to thedesired particle size.

After forming the dispersion, at least a portion of the water may beremoved to form toner particles. In selected embodiments, substantiallyall of the water may be removed to form base toner particles. In oneembodiment, drying of the dispersion may be accomplished by spray dryingthe dispersion. As is known, spray drying involves the atomization of aliquid feedstock into a spray of droplets and contacting the dropletswith hot air in a drying chamber. The sprays are typically produced byeither rotary (wheel) or nozzle atomizers. Evaporation of moisture fromthe droplets and formation of dry particles proceed under controlledtemperature and airflow conditions. Powder is discharged substantiallycontinuously from the drying chamber. Operating conditions and dryerdesign are selected according to the drying characteristics of theproduct and powder specification. Other drying techniques known in theart may also be used, including fluid bed drying, vacuum drying, radiantdrying, and flash drying, among others.

Thus, in one embodiment, a dispersion may be formed, and shipped toanother location, where the dispersion is subjected to a post-treatmentprocess such as spray drying to form a toner powder.

In select embodiments, it is advantageous to add auxiliary fineparticles to the base toner particles in order to improve the fluidity,the electrification stability, or the blocking resistance at a hightemperature, etc. The auxiliary fine particles to be fixed on thesurface of the base toner particles may be suitably selected for useamong various inorganic or organic fine particles.

As the inorganic fine particles, various carbides such as siliconcarbide, boron carbide, titanium carbide, zirconium carbide, hafniumcarbide, vanadium carbide, tantalum carbide, niobium carbide, tungstencarbide, chromium carbide, molybdenum carbide and calcium carbide,various nitrides such as boron nitride, titanium nitride and zirconiumnitride, various borides such as zirconium boride, various oxides suchas titanium oxide, calcium oxide, magnesium oxide, zinc oxide, copperoxide, aluminum oxide, cerium oxide, silica and colloidal silica,various titanate compounds such as calcium titanate, magnesium titanateand strontium titanate, phosphate compounds such as calcium phosphate,sulfides such as molybdenum disulfide, fluorides such as magnesiumfluoride and carbon fluoride, various metal soaps such as aluminumstearate, calcium stearate, zinc stearate and magnesium stearate, talc,bentonite, various carbon black and conductive carbon black, magnetiteand ferrite, may, for example, be employed. As the organic fineparticles, fine particles of a styrene resin, an acrylic resin, an epoxyresin or a melamine resin, may, for example, be employed.

Among such auxiliary fine particles, silica, titanium oxide, alumina,zinc oxide, various carbon black or conductive carbon black may, forexample, be particularly preferably employed. Further, such auxiliaryfine particles may include the above mentioned inorganic or organic fineparticles, where the surface of the particles is treated by surfacetreatment, such as hydrophobic treatment by a treating agent such as asilane coupling agent, a titanate coupling agent, a silicone oil, amodified silicone oil, a silicone varnish, a fluorinated silane couplingagent, a fluorinated silicone oil or a coupling agent having aminogroups or quaternary ammonium bases. Such treating agents may be usedalone or in combination as a mixture of two or more of them.

The above auxiliary fine particles may have an average particle size offrom 0.001 to 3 μm, preferably from 0.005 to 1 μm, and a pluralityhaving different particle sizes may be used in combination. The averageparticle size of the auxiliary fine particles may be obtained byobservation by an electron microscope.

As the above auxiliary fine particles, two or more different types ofauxiliary fine particles may be used in combination. For example,surface-treated particles and non-surface-treated particles may be usedin combination, or differently surface-treated particles may be used incombination. Otherwise, positively chargeable particles and negativelychargeable particles may be suitably combined for use.

As a method for adding the auxiliary fine particles to the base tonerparticles, a method is known to add and blend them by means of a highspeed stirring machine such as a Henschel mixer. However, in order toimprove the blocking resistance at a high temperature, it is preferredto have the auxiliary fine particles fixed on the surface of the basetoner particles. In the present invention, fixing means an additionmethod employing an apparatus capable of exerting a compression sharingstress (hereinafter referred to as a compression shearing treatmentapparatus) or an apparatus capable of melting or softening the surfaceof the base toner particles (hereinafter referred to as a particlesurface-melting treatment apparatus). By such fixing treatment, theauxiliary fine particles may be firmly fixed to the surface of the basetoner particles without substantial pulverization of the base tonerparticles, whereby blocking resistance during storage at a hightemperature may be improved, and it is possible to produce a toner whichis less likely to bring about fusion to components of a copying machineor a printer even in a continuous copying operation.

The above-mentioned compression shearing treatment apparatus isconstructed to have a narrow clearance defined by a head surface and ahead surface, a head surface and a wall surface, or a wall surface and awall surface, which are mutually mobile while a distance is maintained,so that the particles to be treated are forcibly passed through theclearance, whereby a compression stress and a shearing stress will beexerted to the surface of the particles without substantiallypulverizing them. As the compression shearing treatment apparatus to beused, a mechanofusion apparatus manufactured by Hosokawa Micron K.K.,may, for example, be mentioned.

The above-mentioned particle surface-melting treatment apparatus isusually constructed so that a mixture of the base toner fine particlesand the auxiliary fine particles is instantaneously heated to atemperature of at least the melting-initiation temperature by means of,for example, a hot air stream thereby to have the auxiliary fineparticles fixed. As the particle surface-melting treatment apparatus tobe used, a surfusing system manufactured by Nippon Neumatic K.K. may,for example, be mentioned.

In another embodiment, the thermoplastic resin may be formed in acontinuous or in situ polymerization process. In this embodiment, amechanical dispersion or emulsion of monomers in an aqueous solution maybe formed. Polymerization of the monomers may occur either during orafter the emulsification. Additives may be added to the system eitherduring or after the emulsification and/or polymerization. In anotherembodiment, a resin produced by a continuous polymerization process maybe directly coupled to emulsification and finishing processes.

Applications

The toners described above may be used in cartridges, processcartridges, and image forming apparatus. For example, process cartridgesusing toners described herein may include photoconductors, chargingunits, developing units, cleaning units, and may be attached to the mainbody of an image forming apparatus in an attachable and detachablemanner. As another example, toner cartridges may include anelectrostatic image bearing member, and a developing means to form avisible image by developing with a toner a latent electrostatic imageformed on the image bearing member. Image forming apparatus may includea latent electrostatic image bearing member, a latent electrostaticimage forming means, a developing means for developing the electrostaticimage and forming a visible image, a transferring means that transfersthe visible image to a substrate medium, and a fixing means the fixesthe transferred image to the substrate medium. Cartridges, processcartridges, and image forming apparatus are disclosed in, for example,U.S. Pat. Nos. 7,177,582, 7,177,570, 7,169,525, 7,166,401, 7,161,612,6,477,348, 5,974,281, and others.

EXAMPLES

Embodiments of the present invention may have a thermoplastic resincomponent (A) plus stabilizing agent in an amount of about 45% to about99% by weight of the overall toner composition. In other embodiments,this may range from 60% to 80%. Further, embodiments of the presentinvention may use colorant in an amount from greater than about 0% toabout 30% by weight of the overall toner composition. Still further,embodiments of the present invention may use magnetic pigment in anamount from greater than about 0% to about 50% by weight of the overalltoner composition. Still further, embodiments of the present inventionmay use a number of additional additives, in an amount of greater thanabout 0% to about 10% by weight of the overall toner composition.

In one embodiment, the toner may include 5-15 wt. % black pigment, 2-5wt. % polyester resin, 70-85 wt. % styrene butyl acrylate resin, 0.2-0.8wt. % CCA, 5-15 wt. % wax (ester wax), 0.5-2 wt. % silica (may be addedafter toner is made), 0.5-2 wt. % TiO2 (may be added after toner ismade), and 0.5-2 wt. % surfactant (based on solids). In a particularembodiment, the toner may include 9 wt. % black pigment, 3.5 wt. %polyester resin, 77 wt. % styrene butyl acrylate resin, 0.5 wt. % CCA,10 wt. % wax (ester wax), 1 wt. % silica, 1 wt. % TiO2, and 1 wt. %surfactant (based on solids).

In one embodiment, a cyan color toner may be prepared by forming anaqueous dispersion with a 79 wt. % styrene butyl acrylate copolymer, 2wt. % zinc salicylic acid, a charge control agent, 4 wt. % polypropylenewax, 1 wt. % silica powder, 9.5 wt. % pigment dispersion of 30.8 wt. %BFD-1121 pigment blue, 60 wt. % water, and 9.2 wt. % acrylic polymerstabilizer, and 4.5 wt. % Keystone Blue GN, a dry pigment available fromKeystone Aniline Co. The mixture may be extruded and dried to removeexcess water. Post-additive agents that may be included to enhance flowcontrol include 1 wt. % hydrophobic silane-treated silica and 0.7 wt. %hydrophobic titanium dioxide.

In another embodiment, a yellow color toner may be prepared by formingan aqueous dispersion with a 77 wt. % styrene butyl acrylate copolymer,2 wt. % zinc salicylic acid, a charge control agent, 4 wt. %polypropylene wax, 1% silica powder, 11.5 wt. % pigment dispersion of30.8 wt. % YFD-4244 pigment yellow, 60 wt. % water, and 9.2 wt. %acrylic polymer stabilizer, and 4.5 wt. % Clarient Permanent Yellow 17,a dry pigment available from Keystone Aniline Co. The mixture may beextruded and dried to remove excess water. Post-additive agents that maybe included to enhance flow control include 1 wt. % hydrophobicsilane-treated silica and 0.7 wt. % hydrophobic titanium dioxide.

In one embodiment, a magenta color toner may be prepared by forming anaqueous dispersion with a 69 wt. % styrene butyl acrylate copolymer, 2wt. % zinc salicylic acid, a charge control agent, 4 wt. % polypropylenewax, 21 wt. % pigment dispersion of 30.8 wt. % QFD-1146 pigment red, 60wt. % water, and 9.2 wt. % acrylic polymer stabilizer, and 4 wt. %Clarient Hostacopy M-501 Pigment Red 122, a dry pigment available fromKeystone Aniline Co. The mixture may be extruded and dried to removeexcess water. Post-additive agents that may be included to enhance flowcontrol include 1 wt. % hydrophobic silane-treated silica and 0.7 wt. %hydrophobic titanium dioxide.

In yet another embodiment, a magnetic black toner may be prepared byforming an aqueous dispersion with 100 parts polyester, 95 partsmagnetite, 1 part polydimethylsiloxane, and 1 part conductive carbonblack.

Advantageously, embodiments disclosed herein allow for a broad range ofpolymers to be used in toner compositions. Further, embodimentsdisclosed herein may involve a non-solvent, monomer-free process, whichis environmentally superior to prior art processes. Further, embodimentsmay provide for smaller particle sizes, and narrower particle sizedistributions than in the prior art.

While the invention has been described with respect to a limited numberof embodiments, those skilled in the art, having benefit of thisdisclosure, will appreciate that other embodiments can be devised whichdo not depart from the scope of the invention as disclosed herein.Accordingly, the scope of the invention should be limited only by theattached claims.

What is claimed is:
 1. A method for forming a toner, the methodcomprising: forming a compound, the compound comprising: an aqueousdispersion comprising: a thermoplastic resin; wherein the dispersion hasan average volume diameter particle size from about 0.05 to about 10microns; and at least one selected from the group consisting of acolorant and a magnetic pigment; and removing at least a portion of thewater in the dispersion to form toner particles.
 2. The method of claim1, wherein the forming the compound comprises melt kneading anddispersing the thermoplastic resin and optionally additional componentsin an extruder.
 3. The method of claim 1, wherein the forming thecompound comprises; melt kneading the thermoplastic resin and optionallyadditional compounds in a melt kneader to form a resin melt; anddispersing the resin melt in an aqueous phase.
 4. The method of claim 1,wherein the thermoplastic resin is a self-stabilizing resin.
 5. Themethod of claim 1, wherein the dispersion further comprises aneutralizing agent.
 6. The method of claim 5, wherein the dispersionfurther comprises a stabilizing agent.
 7. The method of claim 1, whereinthe dispersion further comprises a stabilizing agent.
 8. The method ofclaim 1, further comprising post-treating the toner particles.
 9. Themethod of claim 8, wherein the removing comprises spray-drying thecompound.
 10. The method of claim 1, wherein the compound furthercomprises at least one of auxiliary fine particles, a charge controlagent, a lubricant, and a polishing agent.
 11. The method of claim 1,wherein the thermoplastic resin comprises at least one polyester formedby reacting an aliphatic diol with a diacid.
 12. A method of using tonerformed in claim 1, the method comprising: disposing the toner formed inclaim 1 in a process cartridge.
 13. The method of claim 12, furthercomprising attaching the process cartridge to an image forming device.